KVM: Remove user_alloc from struct kvm_memory_slot

This field was needed to differentiate memory slots created by the new
API, KVM_SET_USER_MEMORY_REGION, from those by the old equivalent,
KVM_SET_MEMORY_REGION, whose support was dropped long before:

  commit b74a07beed0e64bfba413dcb70dd6749c57f43dc
  KVM: Remove kernel-allocated memory regions

Although we also have private memory slots to which KVM allocates
memory with vm_mmap(), !user_alloc slots in other words, the slot id
should be enough for differentiating them.

Note: corresponding function parameters will be removed later.

Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

3 files changed, 16 insertions, 23 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 373e17a0d398..3c5bb6fe5280 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6897,33 +6897,28 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
                                 bool user_alloc)
 {
         int npages = memslot->npages;
-        int map_flags = MAP_PRIVATE | MAP_ANONYMOUS;
 
-        /* Prevent internal slot pages from being moved by fork()/COW. */
-        if (memslot->id >= KVM_USER_MEM_SLOTS)
-                map_flags = MAP_SHARED | MAP_ANONYMOUS;
-
-        /*To keep backward compatibility with older userspace,
-         *x86 needs to handle !user_alloc case.
+        /*
+         * Only private memory slots need to be mapped here since
+         * KVM_SET_MEMORY_REGION ioctl is no longer supported.
          */
-        if (!user_alloc) {
-                if (npages && !old.npages) {
-                        unsigned long userspace_addr;
+        if ((memslot->id >= KVM_USER_MEM_SLOTS) && npages && !old.npages) {
+                unsigned long userspace_addr;
 
-                        userspace_addr = vm_mmap(NULL, 0,
-                                                 npages * PAGE_SIZE,
-                                                 PROT_READ | PROT_WRITE,
-                                                 map_flags,
-                                                 0);
+                /*
+                 * MAP_SHARED to prevent internal slot pages from being moved
+                 * by fork()/COW.
+                 */
+                userspace_addr = vm_mmap(NULL, 0, npages * PAGE_SIZE,
+                                         PROT_READ | PROT_WRITE,
+                                         MAP_SHARED | MAP_ANONYMOUS, 0);
 
-                        if (IS_ERR((void *)userspace_addr))
-                                return PTR_ERR((void *)userspace_addr);
+                if (IS_ERR((void *)userspace_addr))
+                        return PTR_ERR((void *)userspace_addr);
 
-                        memslot->userspace_addr = userspace_addr;
-                }
+                memslot->userspace_addr = userspace_addr;
         }
 
-
         return 0;
 }
 
@@ -6935,7 +6930,7 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 
         int nr_mmu_pages = 0, npages = mem->memory_size >> PAGE_SHIFT;
 
-        if (!user_alloc && !old.user_alloc && old.npages && !npages) {
+        if ((mem->slot >= KVM_USER_MEM_SLOTS) && old.npages && !npages) {
                 int ret;
 
                 ret = vm_munmap(old.userspace_addr,
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0350e0d5e031..722cae78bbc4 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -273,7 +273,6 @@ struct kvm_memory_slot {
         unsigned long userspace_addr;
         u32 flags;
         short id;
-        bool user_alloc;
 };
 
 static inline unsigned long kvm_dirty_bitmap_bytes(struct kvm_memory_slot *memslot)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2e93630b4add..adc68feb5c5a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -839,7 +839,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
 
         r = -ENOMEM;
         if (change == KVM_MR_CREATE) {
-                new.user_alloc = user_alloc;
                 new.userspace_addr = mem->userspace_addr;
 
                 if (kvm_arch_create_memslot(&new, npages))